JP7115157B2 - Discharge device, image forming device, curing method and program - Google Patents

Description

The present invention relates to an ejection device, an image forming apparatus, a curing method, and a program.

2. Description of the Related Art Conventionally, there has been known an inkjet device that forms an image using an active energy ray-curable liquid such as UV (ultraviolet) curable ink. In addition, in such a UV-curing type inkjet device, a technique is known in which gloss coating is performed with clear ink in order to make printed matter look glossy.

Normally, color printing in a UV curing type inkjet device is performed by irradiating and curing the ink immediately after ejection. However, when performing gloss coating, the clear ink is not irradiated immediately after ejection, but the clear ink is applied. After leveling (smoothing), UV irradiation is performed. At this time, if the clear ink has the same composition as the color ink, when the clear ink is jetted onto the color coating film for leveling, the clear ink dissolves the color coating film unless the clear ink is cured immediately after leveling. end up Therefore, in order to prevent dissolution, clear ink discharge and irradiation must be performed in a series of processes. In order to perform gloss coating in such a series of processes, two irradiators are used: a color UV irradiator that irradiates UV immediately after discharging color ink, and a clear UV irradiator that irradiates UV after clear ink is leveled. or a configuration in which one illuminator is partially extinguished to obtain an effect equivalent to that of two illuminators.

For example, in a configuration in which one irradiator is partially extinguished to obtain an effect equivalent to that of two irradiators, a portion to be partially irradiated (lighted) and a portion to be extinguished correspond to the head configuration and the number of scans. should be provided. As a technique for providing a portion to be partially irradiated (lighted) and a portion to be extinguished, in n passes, discharge is performed up to n−m times and irradiation is performed immediately after, and the clear ink is leveled at the mth pass. , and a technique of obtaining gloss by irradiating leveled clear ink in the remaining passes (see Patent Document 1).

However, in the technique of Patent Document 1, in order to perform lighting control of partial irradiation with the same width as the scan width, irradiation and extinguishing are performed accurately for each scan, and lighting control corresponding to such a number of scans is possible. Such an irradiator needs to be newly developed, and there is a problem that the cost is higher than when a general-purpose irradiator is used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to perform gloss coating with high precision at low cost.

In order to solve the above-described problems and achieve the object, the present invention ejects an active energy ray-curable liquid onto a recording medium from a first ejection portion among ejection portions that move in a main scanning direction. an ejection control unit, an irradiation unit that irradiates an active energy ray and is divided into a plurality of irradiation blocks in a sub-scanning direction orthogonal to the main scanning direction, and one of the plurality of irradiation blocks that moves in the main scanning direction. and an irradiation control unit that turns off a first irradiation block corresponding to the first ejection unit, wherein the irradiation unit is in an extinguished state corresponding to the first ejection unit among the plurality of irradiation blocks. A second irradiation block adjacent to the downstream side of one irradiation block in the sub-scanning direction, and the sub-scanning from the downstream end of the first discharge section in the sub- scanning direction to the upstream end of the second irradiation block A first distance in the direction is larger than a second distance for irradiating the recording medium outward in the sub-scanning direction from an end portion of the irradiation surface of the second irradiation block when the second irradiation block irradiates. and the irradiation control unit cures the liquid by irradiating the active energy ray from the second irradiation block.

According to the present invention, gloss coating can be performed with high precision at low cost.

FIG. 1 is a diagram illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment; FIG. 2 is a side view of the image forming apparatus according to the embodiment; FIG. 3 is a top view of the image forming apparatus according to the embodiment. FIG. 4 is a bottom view of main parts (main scanning unit and irradiation unit) of the image forming apparatus according to the embodiment. FIG. 5 is a side cross-sectional view of main parts (main scanning unit and irradiation unit) of the image forming apparatus according to the embodiment. FIG. 6 is a diagram illustrating an example of a functional block configuration of an image forming apparatus (controller unit) according to the embodiment; FIG. 7 is a diagram showing an example of drive signals and ink ejection amounts in the image forming apparatus according to the embodiment. FIG. 8 is a diagram illustrating an example of the relationship between the irradiation distance and the irradiation width of UV light emitted from the irradiation unit of the image forming apparatus according to the embodiment. FIG. 9 is an enlarged bottom view of the main scanning unit and the irradiation unit of the image forming apparatus according to the embodiment. FIG. 10 is a diagram illustrating an example of the arrangement relationship between the head unit and the irradiation unit when image forming processing is performed in the gloss coat mode when Y<C in the image forming apparatus according to the embodiment. FIG. 11 is a diagram illustrating an example of an arrangement relationship when the irradiation unit is moved with respect to the head unit when the image forming apparatus according to the embodiment operates in the gloss coat mode. FIG. 12 is a diagram illustrating a case where the scan width is made larger than the width of the irradiation block. FIG. 13 is a flowchart illustrating an example of the flow of image forming processing (including hardening processing) of the image forming apparatus according to the embodiment. FIG. 14 is a diagram illustrating an example of arrangement of irradiation units of an image forming apparatus according to a modification.

Embodiments of an ejection device, an image forming apparatus, a curing method, and a program according to the present invention will be described in detail below with reference to FIGS. 1 to 14. FIG. In addition, the present invention is not limited by the following embodiments, and the constituent elements in the following embodiments can be easily conceived by those skilled in the art, substantially the same, and so-called equivalent ranges. is included. Furthermore, various omissions, replacements, changes, and combinations of components can be made without departing from the gist of the following embodiments.

(Overall Configuration of Image Forming Apparatus)
FIG. 1 is a diagram illustrating an example of a hardware configuration of an image forming apparatus according to an embodiment; FIG. 2 is a side view of the image forming apparatus according to the embodiment; FIG. 3 is a top view of the image forming apparatus according to the embodiment. An overall configuration (hardware configuration) of an image forming apparatus according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG.

As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes a controller unit 3, a detection group 4, a main scanning unit 100, a sub-scanning unit 200, a head unit 300 (ejection section), an irradiation A unit 400 (irradiation unit) and a maintenance unit 500 are provided.

The controller unit 3 is a device that controls the operation of each unit of the image forming apparatus 1 . The controller unit 3 includes a unit control circuit 31, a ROM (Read Only Memory) 32, a memory 33, a CPU (Central Processing Unit) 34, and an I/F (Interface) 35, as shown in FIG. I have. Note that the “ejection device” according to the present invention may be, for example, a device including at least the controller unit 3 and the irradiation unit 400 .

The unit control circuit 31 is a circuit that controls operations of the main scanning unit 100, the sub-scanning unit 200, the head unit 300, the irradiation unit 400, and the maintenance unit 500 according to instructions from the CPU .

The CPU 34 controls the overall operation of the image forming apparatus 1 by executing a program stored in the ROM 32 using the memory 33 as a work area. Specifically, the CPU 34 controls operations of the main scanning unit 100 , the sub-scanning unit 200 , the head unit 300 , the irradiation unit 400 and the maintenance unit 500 via the unit control circuit 31 . Further, the CPU 34 controls each unit described above based on the recording data received from the PC (Personal Computer) 2 shown in FIG. to form

The I/F 35 is an interface for connecting the image forming apparatus 1 to the external PC 2 for data communication. Although the I/F 35 of the image forming apparatus 1 is directly connected to the PC 2 in FIG. 1, the present invention is not limited to this. Data communication with the PC 2 may be performed by communication.

A printer driver is installed in the PC 2, and print data to be transmitted to the image forming apparatus 1 is generated from the image data by the printer driver. The print data includes command data for operating the sub-scanning unit 200 and the like of the image forming apparatus 1 and pixel data relating to the image. The pixel data is composed of, for example, 2-bit data for each pixel, and is expressed in 4 gradations.

A detection group 4 includes various sensors necessary for the operation of the image forming apparatus 1 . For example, the detection group 4 includes a height sensor 41 and the like shown in FIGS. 4 and 5, which will be described later.

The main scanning unit 100 is a unit that moves in the Z-axis direction (height direction) shown in FIG. 2 and in the X-axis direction (main scanning direction) shown in FIGS. is. When moving in the main scanning direction, the main scanning unit 100 is moved in the main scanning direction by a timing belt 101 (see FIGS. 2 and 3) that is hung on a pulley (not shown) and extends in the main scanning direction.

In accordance with the drive signal from the unit control circuit 31, the sub-scanning unit 200 moves the substrate 201 (an example of the recording medium) placed on the sub-scanning unit 200 shown in FIGS. 2 and 3, as shown in FIG. This is a unit that moves in the Y-axis direction (sub-scanning direction). Further, the sub-scanning unit 200 has a suction mechanism, which suctions and fixes the base material 201 placed by the user.

The head unit 300 uses Y (yellow), M (magenta), C (cyan), K (black), CL (clear), and W (white) UV curable ink (an example of active energy ray curable ink). is a unit composed of heads for ejecting . The head unit 300 is provided on the bottom surface of the main scanning unit 100 . The arrangement configuration of each head of the head unit 300 will be described later with reference to FIGS. 4 and 5. FIG.

Each head of the head unit 300 includes a piezo element (piezoelectric element), and when a drive signal is applied to the piezo element from the unit control circuit 31, it undergoes a contraction motion. A UV curable ink is ejected onto the substrate. This forms an inked surface on the substrate. In addition, as the UV curable ink according to the present embodiment, for example, an ink containing an acrylate-based monomer or a methacrylate-based monomer can be used. Methacrylate-based monomers have the advantage of being relatively weak in skin sensitization, but have the characteristic of having a greater degree of curing shrinkage than general inks.

The irradiation units 400 are provided on two sides perpendicular to the X-axis direction (main scanning direction) of the main scanning unit 100, and emit UV light (an example of active energy rays) according to a drive signal from the unit control circuit 31. It is a unit that emits light. The irradiation unit 400 mainly includes a UV irradiation lamp that emits UV light. This UV irradiation lamp is realized by, for example, an LED (Light Emitting Diode). The irradiation units 400, as shown in FIGS. 2 and 3, are an irradiation unit 400L provided on one side surface perpendicular to the X-axis direction (main scanning direction) of the main scanning unit 100, and an irradiation unit 400L provided on the other side surface. and an irradiation unit 400R.

The maintenance unit 500 is a unit that cleans (maintains) each head of the head unit 300 of the main scanning unit 100 moved above the maintenance unit 500 in order to maintain and recover the performance of each head of the head unit 300 . Specifically, the maintenance unit 500 has a wiper unit 501, as shown in FIGS. The wiper unit 501 rises and moves in the sub-scanning direction to wipe off the ink adhering to the surface of each head when discharged.

Note that the hardware configuration of the image forming apparatus 1 shown in FIG. 1 is an example, and does not need to include all the components shown in FIG. 1, or may include other components.

(Details of head unit and irradiation unit configuration)
FIG. 4 is a bottom view of main parts (main scanning unit and irradiation unit) of the image forming apparatus according to the embodiment. FIG. 5 is a side cross-sectional view of main parts (main scanning unit and irradiation unit) of the image forming apparatus according to the embodiment. Details of the configurations of the head unit 300 and the irradiation unit 400 of the image forming apparatus 1 according to the present embodiment will be described with reference to FIGS. 4 and 5. FIG.

As shown in FIGS. 4 and 5 , a head unit 300 that ejects UV curable ink (hereinafter sometimes simply referred to as “ink”) is provided on the bottom surface of the main scanning unit 100 . The head unit 300 includes heads 301CM1 to 301CM3 that eject color inks of C (cyan) and M (magenta), heads 301YK1 to 301YK3 that eject color inks of Y (yellow) and K (black), and heads 301YK1 to 301YK3 that eject color inks of W (white). It includes heads 301W1 to 301W3 for ejecting color ink, and heads 301CL1 to 301CL3 for ejecting clear ink for performing gloss coating. Note that each head of the head unit 300 described above is simply referred to as "head 301" when indicating an arbitrary head or when collectively referring to each head.

As shown in FIG. 4, each head 301 has four nozzle rows in which a plurality of nozzle holes through which ink is ejected are arranged in the sub-scanning direction. Of these, the head 301CM1 is composed of an ejection section 301C1 configured with two rows of nozzles for ejecting C (cyan) color ink and two rows of nozzles for ejecting M (magenta) color ink. and a discharge portion 301M1. Similarly, the head 301CM2 includes a discharge section 301C2 and a discharge section 301M2, and the head 301CM3 includes a discharge section 301C3 and a discharge section 301M3. The head 301YK1 has an ejection unit 301Y1 configured with two rows of nozzles for ejecting Y (yellow) color ink, and an ejection unit 301Y1 configured with two rows of nozzles for ejecting K (black) color ink. and a part 301K1. Similarly, the head 301YK2 includes an ejection section 301Y2 and an ejection section 301K2, and the head 301YK3 includes an ejection section 301Y3 and an ejection section 301K3.

The W (white) color ink ejected by the heads 301W1 to 301W3 is used for the substrate 201 other than the white background. Also, the clear ink ejected by the heads 301CL1 to 301CL3 is used to form a gloss coat layer on the base material 201 or the color ink applied to the base material 201 . The ink ejected from the heads 301CL1 to 301CL3 to form the gloss coat layer is not limited to clear ink, which is colorless. There may be.

As shown in FIG. 4, the heads 301 for each color are arranged in the sub-scanning direction such that the three heads are mutually shifted in the main scanning direction. For example, the heads 301W1 to 301W3 that eject W (white) color ink are arranged in the sub-scanning direction in a manner that they are shifted from each other in the main scanning direction. By arranging the heads 301 for each color as described above, the length H in the sub-scanning direction for ejecting each color ink is determined as shown in FIG.

Further, as shown in FIGS. 4 and 5, a height sensor 41 is provided on the lower surface of the main scanning unit 100. As shown in FIG. The height sensor 41 measures the distance (gap) to the substrate 201 , that is, the height of the lower surface of the main scanning unit 100 with respect to the substrate 201 . Based on the gap measured by the height sensor 41, the main scanning unit 100 moves the Z direction until the gap between the main scanning unit 100 (head unit 300) and the substrate 201 reaches a target set value (for example, 1 mm). Move axially.

As described above, the irradiation unit 400 includes the irradiation unit 400L and the irradiation unit 400R on the sides of the main scanning unit 100 perpendicular to the X-axis direction. The irradiation unit 400L and the irradiation unit 400R are each divided into a plurality of irradiation blocks, and each irradiation block can independently control the output of the LED. In the example shown in FIG. 4, the irradiation block 401L is divided into nine irradiation blocks (irradiation blocks 401L1 to 401L9). The irradiation blocks 401L1 to 401L9 are simply referred to as "irradiation block 401L" when indicating arbitrary irradiation blocks or collectively. Also, the irradiation block 401R is divided into nine irradiation blocks (irradiation blocks 401R1 to 401R9). Note that the irradiation blocks 401R1 to 401R9 are simply referred to as "irradiation block 401R" when indicating arbitrary irradiation blocks or collectively. Also, the range of each irradiation block is, for example, the range from the most upstream to the downstream in the sub-scanning direction.

As shown in FIGS. 4 and 5, the irradiation unit 400L and the irradiation unit 400R are each connected to a lamp moving mechanism 402 (an example of an irradiation moving section). The lamp moving mechanism 402 is connected to a lamp fixing mechanism 403 fixed to the main scanning unit 100 and a guide rail 404 . The irradiation unit 400L and the irradiation unit 400R are fixed to the lamp fixing mechanism 403 by fitting the lamp fixing pins 405L and 405R into the holes drilled in the lamp moving mechanism 402 and the lamp fixing mechanism 403, respectively. . Also, the irradiation unit 400L (400R) is released from the lamp fixing mechanism 403 by removing the lamp fixing pin 405L (405R) from the lamp moving mechanism 402. FIG. When the irradiation unit 400L (400R) is released from the lamp fixing mechanism 403, it becomes manually movable along the guide rail 404, that is, in the sub-scanning direction. After the irradiation unit 400L (400R) is moved to an arbitrary position in the sub-scanning direction, it can be fixed to the lamp fixing mechanism 403 by the lamp fixing pin 405L (405R). As a result, the irradiation unit 400L (400R) can irradiate the ink applied to the base material 201 with UV light at any position fixed in the sub-scanning direction.

In the above description, an example in which the irradiation unit 400L (400R) is manually moved in the sub-scanning direction with respect to the main scanning unit 100 (lamp fixing mechanism 403) has been described, but the present invention is not limited to this. That is, the lamp moving mechanism 402 is provided with an actuator (an example of an irradiation moving unit) that moves the irradiation unit 400L (400R) in the sub-scanning direction, and the irradiation unit 400L (400R) is automatically moved to any position in the sub-scanning direction. It may be movable.

Next, an outline of image forming processing (including curing processing) of the image forming apparatus 1 according to this embodiment will be described.

First, the sub-scanning unit 200 moves in the sub-scanning direction (Y-axis direction) according to a drive signal from the CPU 34 (unit control circuit 31) to move the base material 201 to an initial value for forming an image.

Next, the main scanning unit 100 adjusts the height (for example, the gap between the head unit 300 and the substrate 201) suitable for the ejection of the UV curable ink by the head unit 300 according to the drive signal from the CPU 34 (unit control circuit 31). is 1 mm). In this case, the height of the head unit 300 with respect to the base material 201 is recognized by the CPU 34 based on the height detection data detected by the height sensor 41 .

Next, the main scanning unit 100 reciprocates (scans) in the main scanning direction (X-axis direction) according to drive signals from the CPU 34 (unit control circuit 31). When the main scanning unit 100 reciprocates, the head unit 300 ejects color ink (energy curable colored liquid) according to a drive signal from the CPU 34 (unit control circuit 31). As a result, an image for one scan (one scan) is formed on the base material 201 . Furthermore, the color ink ejected onto the base material 201 during the reciprocating movement of the main scanning unit 100 is cured by irradiation with UV light from the irradiation unit 400 . Subsequently, the sub-scanning unit 200 moves the width of one scan (one scan) in the sub-scanning direction (Y-axis direction) (hereinafter referred to as “scanning width”) according to the drive signal from the CPU 34 (unit control circuit 31). is) (scanning width). Thereafter, the operation of forming an image for one scan and the operation of moving the sub-scanning unit 200 by the scan width in the sub-scanning direction are alternately performed until the formation of the image is completed.

In addition, when a gloss coat is performed with clear ink, the time for smoothing (leveling) the clear ink (hereinafter referred to as "leveling time") is not performed by irradiating UV light to cure the clear ink immediately after it is ejected. ), and then UV light is emitted from the irradiation unit 400 to cure the leveled clear ink and form a gloss coating layer.

(Function configuration of controller unit)
FIG. 6 is a diagram illustrating an example of a functional block configuration of an image forming apparatus (controller unit) according to the embodiment; FIG. 7 is a diagram showing an example of drive signals and ink ejection amounts in the image forming apparatus according to the embodiment. FIG. 8 is a diagram illustrating an example of the relationship between the irradiation distance and the irradiation width of UV light emitted from the irradiation unit of the image forming apparatus according to the embodiment. The configuration of the functional blocks of the controller unit 3 of the image forming apparatus 1 according to this embodiment will be described with reference to FIGS. 6 to 8. FIG.

As shown in FIG. 6 , the controller unit 3 according to this embodiment has a movement control section 601 , a droplet discharge control section 602 (discharge control section), and an irradiation control section 603 .

Movement control section 601 causes unit control circuit 31 to apply drive signals to main scanning unit 100 and sub-scanning unit 200, and main scanning unit 100 moves in the Z-axis direction (height direction) and X-axis direction (main scanning direction). ) to move the sub-scanning unit 200 in the Y-axis direction (sub-scanning direction). The movement control unit 601 is implemented by, for example, a program executed by the CPU 34 shown in FIG.

The droplet ejection control unit 602 is a functional unit that controls the ink ejection operation of the head unit 300 . The droplet ejection control section 602 causes the unit control circuit 31 to apply, for example, a drive signal as shown in FIG. 7, "no ejection", "small dot", "medium dot" and "large dot"). The droplet ejection control unit 602 selects a mask signal and determines the ejection amount based on the gradation of the pixel. The droplet ejection control unit 602 is realized by, for example, a program executed by the CPU 34 shown in FIG.

The irradiation control unit 603 is a functional unit that causes the unit control circuit 31 to apply a drive signal to the irradiation unit 400, and controls the UV light irradiation operation for each irradiation block 401L and each irradiation block 401R of the irradiation unit 400. .

Here, FIG. 8 shows a mode of UV light emitted from a specific irradiation block 401L (401R) of the irradiation unit 400. As shown in FIG. The UV light emitted from the irradiation block 401L (401R) spreads radially as shown in FIG. FIG. 8 shows a state in which the UV light emitted from the irradiation block 401L (401R) spreads in the sub-scanning direction. Assuming that the width of the UV light in the sub-scanning direction immediately after being irradiated from the irradiation surface of the irradiation block 401L (401R) is the irradiation width L1, as shown in FIG. It can be seen that the irradiation width (irradiation range) in the scanning direction is also widened. In this case, the longer the irradiation distance of the UV light, the more the UV light diffuses and the illuminance decreases.

Here, when the height of the irradiation surface of the irradiation block 401L (401R) with respect to the base material 201 (hereinafter sometimes simply referred to as “the height of the irradiation surface”) is h, the UV light sub- The irradiation width Lh in the scanning direction is larger than the irradiation width L1. That is, the irradiation width Lh has a portion Lr/2 (Lr=Lh−L1) protruding from the irradiation width L1, and the influence of ink curing by the UV light on this protruding portion Lr/2 is considered. There is a need. Details of this will be described later with reference to FIGS. 10 to 12. FIG.

(Adjusting the position of the irradiation unit when operating in gloss coat mode)
FIG. 9 is an enlarged bottom view of the main scanning unit and the irradiation unit of the image forming apparatus according to the embodiment. FIG. 10 is a diagram illustrating an example of the arrangement relationship between the head unit and the irradiation unit when image forming processing is performed in the gloss coat mode when Y<C in the image forming apparatus according to the embodiment. FIG. 11 is a diagram illustrating an example of an arrangement relationship when the irradiation unit is moved with respect to the head unit when the image forming apparatus according to the embodiment operates in the gloss coat mode. Adjustment of the position of the irradiation unit 400 when operating in the gloss coat mode in the image forming apparatus 1 according to the present embodiment will be described with reference to FIGS. 9 to 11. FIG. Here, the term "gloss coat mode" refers to an operation mode in which after an image is formed with color inks, a glossy image is formed by forming a gloss coat layer by ejecting clear ink thereon. . 9 to 11, of the irradiation units 400L and 400R constituting the irradiation unit 400, the irradiation unit 400R will be focused on and explained.

As shown in the enlarged view of FIG. 9, in addition to the length H in the sub-scanning direction in which the ink of the color is ejected by the head 301 of each color described above, the length in the sub-scanning direction of the irradiation unit 400 (400R) is L , the length of one irradiation block 401R in the sub-scanning direction is B, and the most downstream side of the head 301 in the sub-scanning direction (lower side in FIG. (the side to be scanned last for a specific area of ) is downstream from the end of the irradiation block (in the example shown in FIG. 9, the irradiation block 401R9) that is lit on the downstream side in the irradiation unit 400R. If the distance to the end is Y (first distance), then L=H+Y+B.

In the example shown in FIG. 9, the irradiation blocks 401R1 to 401R3 and 401R9 among the irradiation blocks 401R of the irradiation unit 400R are illuminated, and the irradiation blocks 401R4 to 401R8 are extinguished. In this case, as will be described later, the UV light irradiated by the irradiation block 401R9 responsible for curing the clear ink has a protruding portion based on the irradiation distance to the base material 201 as described above with reference to FIG. Therefore, the irradiation block 401R9 is positioned outside the substrate 201 by a distance C (second distance) in the sub-scanning direction shown in FIG. will be irradiated to The distance C varies depending on the height of the irradiation surface of the irradiation unit 400 and the illuminance, as described above with reference to FIG. For example, when the illuminance is 4.5 W/cm ² (accumulated 1250 mJ/cm ² ) and the height of the irradiation block 401R and the irradiation surface is 2 mm, the distance C is 2 mm.

Next, referring to FIG. 10, the image forming process in the gloss coat mode when Y<C will be described. In the example shown in FIG. 10, when performing image forming processing in the gloss coat mode, that is, when forming a gloss coat layer with clear ink on a color image formed with color ink, first, CMYK color inks are applied. A head 301CM1 and a head 301YK1 (an example of a second ejection unit) are used as the head 301 that ejects and forms an image. At that time, since the color ink is irradiated with UV light immediately after being discharged, irradiation blocks 401R1 to 401R3 which are the irradiation block 401R in which the scan widths of the scans (1 scan to 4 scans) for discharging the color ink overlap. are respectively in a lighting state (irradiation state). At this time, unless a dedicated irradiation lamp corresponding to the scan width based on the number of scans is manufactured, the scan width and the length of one irradiation block 401R (length B described above) are generally different. be.

In addition, the color coating film formed by ejecting the color ink is in an uneven state (matte state) because the UV light is irradiated immediately after the color ink is ejected. Heads 301CL2 and 301CL3 (an example of a first ejection section, an example of a specific ejection section) are used as the head 301 that ejects an energy curable liquid). At this time, since clear ink ejection and image formation with color ink are performed in a series of operations, the width of the scan for ejection of clear ink by the heads 301CL2 and 301CL3 is the width of the scan for ejection of color ink. is the same as The ejection of clear ink from the heads 301CL2 and 301CL3 is performed in 5 to 12 scans. At this time, the irradiation control unit 603 extinguishes the irradiation blocks 401R4 to 401R8 which are the irradiation block 401R in which the scan widths of the scans (5 scans to 12 scans) for clear ink ejection overlap. As a result, the clear ink is sufficiently leveled without being irradiated with UV light immediately after ejection.

After that, UV light irradiation for curing the sufficiently leveled clear ink is performed by 13 scans and 14 scans. At this time, the irradiation block 401R9, which is the irradiation block 401R in which the scan widths of the scans (13th scan and 14th scan) for UV light irradiation overlap, is turned on (irradiated state). As a result, the leveled clear ink is irradiated with UV light to form a gloss coating layer.

However, in the case of Y<C in FIG. 10, the clear ink ejected by the head 301CL3 should be leveled in the 12th scan, but since Y<C, the area of the 12th scan is not irradiated. Part of the irradiation light of the block 401R9 (protruding portion) is irradiated, and the downstream side (lower side in the sub-scanning direction in FIG. 10) of the portion where the clear ink is ejected is not sufficiently leveled and cured into a matte state. turn into.

Therefore, in order to obtain a glossy gloss coating layer, the user moves the irradiation unit 400R in the sub-scanning direction so that Y>C as shown in FIG. Note that not only the irradiation unit 400R but also the irradiation unit 400L is moved in the same manner. As a result, in the 12th scan, the clear ink ejected by the head 301CL3 is not irradiated with part of the irradiation light from the irradiation block 401R9 (protruding portion) in the area of the 12th scan, so that it is sufficiently leveled. and can form a glossy gloss coating layer on top of the color coating.

Also, in FIG. 11, in the fifth scan, the irradiation block 401R3 is turned on, so that after the clear ink is ejected by the head 301CL2, the upstream portion is immediately cured and becomes matte. However, after that, the clear ink is ejected in other scans (6 scans to 12 scans) and is sufficiently leveled, so that a glossy gloss coating layer is formed on the matte clear ink. In addition, since the irradiation block 401R3 in the lighting state corresponds to the boundary portion 701 indicating the boundary between the ejection of the color ink and the ejection of the color ink, the color ink is surely irradiated with the UV light, so that the color ink is clean. A color image can be obtained.

Also, as shown in FIG. 11, A is the distance between the most upstream end of H, which is the length of each color ink in the sub-scanning direction, and the most upstream end of the irradiation block 401R (irradiation unit 400). In this case, it is desirable to move the irradiation unit 400R in the sub-scanning direction so that A<C<Y. Assuming that the condition A<C is maintained, in the first scan, the upstream end portion of the color coating film formed by the color inks ejected by the heads 301CM1 and 301YK1 is also irradiated with UV light from the irradiation block 401R1. It becomes difficult for the color inks to coalesce, and a clear color image can be obtained.

In the example of FIG. 11, the head 301CM1 and the head 301YK1 are used as the head 301 that ejects CMYK color inks to form an image, and the heads 301CL2 and 301CL3 are used as the head 301 that ejects clear ink. Indicated. However, for example, as an example of an image forming process using W (white) color ink, a head 301W1 is used as the head 301 that ejects W (white) color ink, and a head 301W1 is used as the head 301 that ejects CMYK color ink. An operation mode in which the head 301CM2 and the head 301YK2 are used and the head 301CL3 is used as the head 301 that ejects clear ink is also conceivable. In this case, in the example of FIG. 11, the boundary portion between the ejection of color ink and the ejection of color ink corresponds to the vicinity of the boundary between the irradiation block 401R5 and the irradiation block 401R6. In this case, the irradiation unit 400R (400L) is moved in the sub-scanning direction so that the boundary portion corresponds to the irradiation block 401R5 in the irradiation state within the range where A<C<Y is satisfied as described above. do it. As a result, a glossy gloss coating layer can be formed on the matte clear ink, and the color ink can be reliably irradiated with UV light, so that a clear color image can be obtained.

FIG. 12 is a diagram illustrating a case where the scan width is made larger than the width of the irradiation block. A case where the scan width is made larger than the length B of one irradiation block 401R will be described with reference to FIG. Specifically, the length in the sub-scanning direction of the portion of one head 301 where ink is ejected is set to be the same as the scan width for two scans.

As shown in FIG. 12, when the scan width is larger than the length B of one irradiation block 401R, even if the irradiation block 401R9 emits UV light in the last 7th scan, the adjacent irradiation block 401R8 is extinguished. As a result, unirradiated portions remain in the ejected clear ink, and a partially uncured region remains in the clear ink. Therefore, in order to obtain a sufficiently hardened gloss coating layer, it is desirable to make the scan width smaller than the length B of one irradiation block 401R.

(Flow of Image Forming Process of Image Forming Apparatus)
FIG. 13 is a flowchart illustrating an example of the flow of image forming processing (including hardening processing) of the image forming apparatus according to the embodiment. The flow of image forming processing in the gloss coat mode of the image forming apparatus 1 according to this embodiment will be described with reference to FIG. Note that FIG. 13 focuses on the irradiation unit 400R, but the same applies to the irradiation unit 400L. In FIG. 13, as in the case of FIG. 11 described above, a head 301CM1 and a head 301YK1 are used as the heads 301 that eject CMYK color inks to form an image, and a head that ejects clear ink for performing gloss coating. 301 uses heads 301CL2 and 301CL3. Also, referring to FIG. 13, an operation of forming an image focusing on a specific portion (an area corresponding to one scan width) of the base material 201 will be described.

<Step S11>
The user removes the lamp fixing pin 405R attached to the lamp moving mechanism 402 and the lamp fixing mechanism 403, and moves the irradiation unit 400R in the sub-scanning direction so that A<C<Y. After moving the irradiation unit 400R, the user fixes the irradiation unit 400R to the lamp fixing mechanism 403 by fitting the lamp fixing pin 405R into the lamp moving mechanism 402 and the lamp fixing mechanism 403 again. Then, the process proceeds to step S12.

<Step S12>
The droplet ejection control unit 602 specifies the upstream head 301 among the plurality of heads 301 arranged in the sub-scanning direction as a head that ejects color ink, and the downstream head 301 that ejects clear ink. Identify the ejection head. The irradiation control unit 603 turns on the irradiation block 401R that overlaps each scan width of the scan for ejecting the color ink (irradiation state). In addition, the irradiation control unit 603 turns off the irradiation block 401R in which the scan widths of the scans for clear ink ejection overlap. Then, the movement control section 601 starts repeating the scanning operation of the main scanning unit 100 in the main scanning direction and the movement operation of the sub-scanning unit 200 in the sub-scanning direction. 11, the head 301CM1 and the head 301YK1 are specified as the heads 301 located upstream for ejecting color ink, and the head 301 located downstream for ejecting clear ink. , heads 301CL2 and 301CL3 are specified. Then, the process proceeds to step S13.

<Step S13>
If the next scan operation performed by the main scanning unit 100 is a scan for ejecting color ink (step S13: Yes), the process proceeds to step S14, and if the scan is not for ejecting color ink (step S13: No), go to step S16. Note that in the example of FIG. 11, the 1st to 4th scans correspond to the scans for ejecting color ink.

<Step S14>
The droplet ejection control section 602 causes the head 301CM1 and the head 301YK1 to eject color ink onto the substrate 201 in accordance with the scanning operation of the main scanning unit 100 by the movement control section 601, thereby forming a color image. Then, the process proceeds to step S15.

<Step S15>
Immediately after the droplet discharge control unit 602 discharges the color ink, the irradiation control unit 603 causes the irradiation block 401R in the lighting state corresponding to the scan to irradiate the color coating film of the color ink with UV light. to cure the color ink. The lighting operation of the irradiation block 401R by the irradiation control unit 603 may be a constant lighting state, or a lighting state when the irradiation block 401R scans the color ink to be cured. Then, the process proceeds to step S20.

<Step S16>
If the next scan operation performed by the main scanning unit 100 is a scan for ejecting clear ink (step S16: Yes), the process proceeds to step S17, and if it is not a scan for ejecting clear ink (step S16: No), go to step S19. In the example of FIG. 11, scans 5 to 12 correspond to scans for ejecting clear ink, and scans 13 and 14 correspond to scans for ejecting neither color ink nor clear ink (irradiation of UV light). scan for ).

<Step S17>
In accordance with the scanning operation of the main scanning unit 100 by the movement control unit 601, the droplet ejection control unit 602 applies the clear ink to the base material 201 to the head corresponding to the scan, either the head 301CL2 or the head 301CL3. Dispense against. Then, the process proceeds to step S18.

<Step S18>
Immediately after the clear ink is ejected by the droplet ejection control unit 602, the irradiation control unit 603 turns off the irradiation block 401R corresponding to the scan, so that the clear ink is not irradiated with UV light. , is leveled (smoothed). Then, the process proceeds to step S20.

<Step S19>
In the final scan (13th and 14th scans in the example of FIG. 11), which is neither a scan for ejecting color ink nor a scan for ejecting clear ink, The clear ink is ejected and leveled, and the irradiation control unit 603 causes the irradiation block 401R in the lighting state corresponding to the scan to irradiate the clear ink with UV light. harden. Then, the process proceeds to step S20.

<Step S20>
If the final scanning operation has ended (step S20: Yes), the image forming process has ended, and if the final scanning operation has not ended (step S20: No), the movement control unit 601 moves the base material 201 to the side. It is moved by one scan width in the scanning direction, and the process returns to step S13.

By the operations of steps S11 to S20 described above, the image forming process in the gloss coat mode is executed.

As described above, in the image forming apparatus 1 according to the present embodiment, the irradiation unit 400R (400L) is moved in the sub-scanning direction so that Y>C. As a result, in the most downstream scan in which clear ink is ejected, the clear ink ejected by the most downstream head 301 that ejects clear ink is applied to the scan area by the irradiation block 401R ( 401L) is not irradiated, so that sufficient leveling can be achieved and a glossy gloss coating layer can be formed on the color coating film at low cost. .

Further, in the image forming apparatus 1 according to the present embodiment, the length of the most upstream end of H, which is the length of each color ink in the sub-scanning direction, and the most upstream end of the irradiation block 401R (401L) is set to When A (the third distance), the irradiation unit 400R is moved in the sub-scanning direction so that A<C<Y. Assuming that the condition A<C is maintained, in the first scan, the upstream end portion of the color coating film formed by the color ink ejected by the head 301 is also irradiated with UV light from the irradiation block 401R (401L) on the most upstream side. Because of the irradiation, the color inks are less likely to coalesce, and a clear color image can be obtained.

Further, when the boundary portion between the ejection of the color ink and the ejection of the color ink corresponds to the vicinity of the boundary between the irradiation blocks, the boundary portion corresponds to the irradiation block within the range where A<C<Y is satisfied as described above. It is assumed that the irradiation unit 400R (400L) is moved in the sub-scanning direction so as to correspond to the irradiation block in the irradiation state among the blocks. As a result, a glossy gloss coating layer can be formed on the matte clear ink, and the color ink can be reliably irradiated with UV light, so that a clear color image can be obtained.

Further, in the image forming apparatus 1 according to the present embodiment, the scan width is made smaller than the length B of one irradiation block 401R (401L). As a result, even if the irradiation block 401R (401L) irradiates the UV light in the last scan, the adjacent irradiation block 401R (401L) is turned off, so that the ejected clear ink remains unirradiated. Therefore, it is possible to obtain a fully cured gloss coating layer by avoiding a situation in which a partially uncured region remains in the clear ink.

(Modification)
FIG. 14 is a diagram illustrating an example of an arrangement of irradiation units of an image forming apparatus according to a modification. A modification of the image forming apparatus 1 according to this embodiment will be described with reference to FIG.

As shown in FIG. 14, in the main scanning unit 100 of the image forming apparatus 1 according to this modification, the irradiation surface of the irradiation unit 400R is tilted with respect to the upper surface of the substrate 201 in the sub-scanning direction. is installed. Furthermore, the irradiation unit 400R is mounted so that the portion of the irradiation surface of the irradiation unit 400R on the downstream side in the sub-scanning direction is higher. The manner of mounting the irradiation unit 400L is also the same as that of the irradiation unit 400R.

By tilting the irradiation surface of the irradiation unit 400R (400L) with respect to the upper surface of the base material 201 in the sub-scanning direction in this way, the irradiation distance is extended and the irradiation range is widened. Therefore, even if the length L in the sub-scanning direction of the irradiation unit 400R (400L) is short, partial irradiation by the irradiation block 401R (401L) is possible.

In addition, by tilting the irradiation surface of the irradiation unit 400R so that the portion on the downstream side in the sub-scanning direction is higher, in the scan for curing the clear ink, the irradiation block with low illuminance from the leftmost irradiation block in FIG. Since light is irradiated, differences in curing shrinkage are less likely to occur in the clear ink, and a beautiful gloss coat film can be obtained.

Further, in the above-described embodiments and modifications, when at least one of the functional units of the image forming apparatus 1 is realized by executing a program, the program is preinstalled in a ROM or the like and provided. Further, the programs executed by the image forming apparatus 1 according to the above-described embodiments and modifications are stored as files in an installable format or an executable format on a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD). , CD-R (Compact Disk-Recordable), DVD (Digital Versatile Disc), or other computer-readable recording medium. Further, the program executed by the image forming apparatus 1 according to the above-described embodiment and modifications is stored on a computer connected to a network such as the Internet, and is provided by being downloaded via the network. good too. Further, the programs executed by the image forming apparatus 1 according to the above-described embodiments and modifications may be configured to be provided or distributed via a network such as the Internet. Further, the program executed by the image forming apparatus 1 of the above-described embodiment and modified example has a module configuration including at least one of the above-described functional units. By reading a program from a storage device (eg, ROM 32) and executing it, each of the functional units described above is loaded onto a main storage device (eg, memory 33) and generated.

1 image forming apparatus 2 PC
3 controller unit 4 detection group 31 unit control circuit 32 ROM
33 memory 34 CPU
35 interfaces
41 height sensor 100 main scanning unit 101 timing belt 200 sub-scanning unit 201 base material 300 head unit 301 head 301C1-301C3 discharge section 301CL1-301CL3 head 301CM1-301CM3 head 301K1-301K3 discharge section 301M1-301M3 discharge section 301W1 head 301Y1-301Y3 Discharge part 301YK1-301YK3 Head 400 Irradiation unit 400L Irradiation unit 400R Irradiation unit 401L, 401L1-401L9 Irradiation block 401R, 401R1-401R9 Irradiation block 402 Lamp moving mechanism 403 Lamp fixing mechanism 404 Guide rail 405L, 0 Lamp fixing pin 405L, 405R0 Maintenance unit 501 Wiper unit 601 Movement controller 602 Droplet discharge controller 603 Irradiation controller 701 Boundary part L1 Irradiation width Lh Irradiation width

JP 2015-186918 A

Claims (11)

an ejection control unit that ejects the active energy ray-curable liquid onto the recording medium from the first ejection unit among the ejection units that move in the main scanning direction;
an irradiation unit that irradiates an active energy ray and is divided into a plurality of irradiation blocks in a sub-scanning direction orthogonal to the main scanning direction;
an irradiation control unit for extinguishing a first irradiation block corresponding to the first ejection unit moving in the main scanning direction among the plurality of irradiation blocks;
with
The irradiation unit is
Among the plurality of irradiation blocks, a second irradiation block adjacent to the first irradiation block in the off state corresponding to the first ejection section and adjacent to the downstream side in the sub-scanning direction;
When the second irradiation block irradiates, the first distance in the sub-scanning direction from the downstream end of the first ejection section in the sub-scanning direction to the upstream end of the second irradiation block is arranged so as to be larger than the second distance for irradiating the recording medium outside in the sub-scanning direction from the end of the irradiation surface of
The irradiation control unit is an ejection device that cures the liquid by irradiating the active energy ray from the second irradiation block. The ejection control unit causes an active energy ray-curable colored liquid to be ejected from a second ejection unit located upstream of the first ejection unit among the ejection units,
3. The irradiation control unit cures the colored liquid by irradiating the active energy ray from the irradiation block corresponding to the second ejection unit moving in the main scanning direction among the plurality of irradiation blocks. 1. The ejection device according to 1. In the irradiation section, a third distance from an upstream end of the second ejection section in the sub-scanning direction to an upstream end of the irradiation block located most upstream among the plurality of irradiation blocks is greater than the second distance. 3. A dispensing device according to claim 2, arranged so that . 4. The ejection according to claim 2, wherein the irradiation control section irradiates the active energy ray from the corresponding irradiation block in the main scanning direction to the boundary between the first ejection section and the second ejection section. Device. The ejection device according to any one of claims 1 to 4, wherein a scanning width of said ejection section when scanning in said main scanning direction is smaller than a length of said irradiation block in said sub-scanning direction. The ejection device according to any one of claims 1 to 5, wherein the irradiation section is arranged such that the irradiation surface is inclined in the sub-scanning direction with respect to the recording medium. 7. The ejection device according to claim 6, wherein the irradiation unit is arranged such that a portion of the irradiation surface on the downstream side in the sub-scanning direction is higher than a portion on the upstream side with respect to the recording medium. the discharge section;
a movement control unit that moves the ejection unit in the main scanning direction;
a discharge device according to any one of claims 1 to 7;
image forming apparatus. 9. The image forming apparatus according to claim 8, further comprising an irradiation movement section that allows the irradiation section to move in the sub-scanning direction with respect to the discharge section. an ejection control step of ejecting an active energy ray-curable liquid onto a recording medium from a specific ejection portion among the ejection portions that move in the main scanning direction;
Among a plurality of irradiation blocks obtained by dividing an irradiation unit that irradiates an active energy ray in a sub-scanning direction orthogonal to the main scanning direction, a first irradiation block corresponding to the specific ejection unit that moves in the main scanning direction is turned off. an irradiation control step that causes
a curing step of curing the liquid by irradiating the active energy ray from a second irradiation block adjacent to the downstream side of the first irradiation block in the sub-scanning direction among the plurality of irradiation blocks in the off state; , has
When the second irradiation block irradiates, the first distance in the sub-scanning direction from the downstream end of the specific ejection unit in the sub-scanning direction to the upstream end of the second irradiation block is the arranged outside in the sub-scanning direction from the end of the irradiation surface of the second irradiation block so as to be larger than the second distance for irradiating the recording medium;
Curing method. The recording medium is divided into a plurality of irradiation blocks in a sub-scanning direction orthogonal to the main scanning direction, and a discharge section that moves in the main scanning direction with respect to the recording medium and discharges an active energy ray-curable liquid. and an irradiation unit that irradiates an active energy ray to the ejection device ,
an ejection control step of ejecting an active energy ray-curable liquid onto the recording medium from a specific ejection portion among the ejection portions that move in the main scanning direction;
an irradiation control step of extinguishing a first irradiation block corresponding to the specific ejection unit moving in the main scanning direction among the plurality of irradiation blocks;
a curing step of curing the liquid by irradiating the active energy ray from a second irradiation block adjacent to the downstream side of the first irradiation block in the off state in the sub-scanning direction;
A program for executing
When the second irradiation block irradiates, the first distance in the sub-scanning direction from the downstream end of the specific ejection unit in the sub-scanning direction to the upstream end of the second irradiation block is the arranged outside in the sub-scanning direction from the end of the irradiation surface of the second irradiation block so as to be larger than the second distance for irradiating the recording medium;
program .

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